Electronic article surveillance (EAS) systems are used to control inventory and to prevent theft or unauthorized removal of items tagged with an EAS security label from a controlled area. Such systems may include a system transmitter and a system receiver to establish a surveillance zone (typically entrances and/or exits in retail stores). The surveillance zone is set-up such that an item removed from or brought into the controlled area must traverse the surveillance zone.
An EAS security label is affixed to the controlled item, including, for example, an article of merchandise, product, case, pallet, container, and the like. The label includes a marker or sensor adapted to interact with a first signal that the system transmitter transmits into the surveillance zone. This interaction establishes a second signal in the surveillance zone. The system receiver receives the second signal. If an item tagged with an EAS security label traverses the surveillance zone, the system recognizes the second signal as an unauthorized presence of the item in the controlled area and activates an alarm.